The increased susceptibility of infants to serious, bacterial infections may be related to the metabolic and functional characteristics of neonatal neutrophils. The primary objectives of this project are to completely investigate the properties of neonatal neutrophils, to identify abnormalities of function and to define the biochemical and enzymatic mechanisms responsible for defective function in an attempt to pursue the hypothesis that abnormalities of neonatal neutrophil function are the consequence of increased activity of oxidative metabolism and autooxidation. Neutrophil metabolim and functions will be measured by a battery of assays in infant, maternal and control cells throughout the first month of life. Activities of enzymes responsible for the detoxification of oxygen (superoxide dismutases, catalase, glutathione peroxidase and myeloperoxidase) will be measured. Functions of normal neutrophils, exposed in vitro to oxidative injury, will be compared to those neonatal neutrophils. Evidence for oxidative damage to neutrophils will be documented directly by identifying lipid oxidation/peroxidation products in neonatal, maternal and experimentally oxidized cells, and indirectly by noting the loss of certain enzyme activities as an indicator of organelle damage. The later will also serve to localize the site of injury. It is likely that information linking autooxidation with neutrophil dysfunction is applicable to the function of neutrophils from cancer patients, toxic neutrophils, neutrophils collected by adhesion for transfusion and conditions characterized by neutrophil-mediated issue injury.